/sci/ - Science & Math

>>2638278
Einstein's theory of general relativity states that light doesn't necessarily travel in straight lines; instead, it follows contours of the surface of space time, called GEODESICS. On a flat plane, geodesics happen to be lines. This mean that two ants, marching on parallel lines, will always stay the same distance apart. Likewise, in a flat universe, two parallel light rays will always stay the same distance apart as they approach and observer. But on a surface with positive curvature, the term parallels doesn't make any sense. Geodesics on a sphere are great circles, like lines of longitude. If two ants at the North Pole began marching down lines of longitude, they would start out inches away from each other and wind up separated by miles and miles. In a positively curved universe, this effect distorts the apparent size of distant objects; incoming rays, in a sense, are spread father apart so objects look bigger than they normally would. On a surface with negative curvature, like a saddle, the opposite is true, making distant objects look smaller than usual.

this works pretty well for Astrophysics